The overall objective of this project is characterization of sperm maturation in the epididymis. Pre-epididymal sperm are non-motile and non- fertile while post-epididymal sperm are motile and fertile. We propose to study biochemical changes which occur during this epididymal transit. The objective of the proposed research are to perfect techniques for isolating pre-epididyml, caput-, corpus- or cauda-epididymal and post-epididymal sperm and to compare several biochemical parameters of these cells. Isolation technique will include cannulation of rate testis, elutriation of testicular homogenates, expression of sperm from epididymal tissue, cannulation of vas deferens and electroejaculation. Specific biochemical comparisons will involve: 1. the relative importance of endogenous and exogenous metabolism for maintenance of ATP levels. 2. the degree of membrane association of enzymes. 3. the uptake of carbohydrates by sperm. 4. changes in levels of cAMP, ATP and enzymes associated with motility. 5. the hydrolytic enzymes associated with the acrosome. All of the above appear to be essential to the function of the mature capacitated sperm.